a. Field of the Invention
The present invention relates to a light bar leveler, and in particular, a leveling means for leveling a freely suspended light bar to which is mounted one or more light fixtures.
b. Problems in the Art
Large lighting fixtures generally include a large, bulky reflector means for capturing and redirecting light to a target area. The reflectors generally surround the bulb or lamp, which in turn is mounted in a socket means or bulb cone to which electrical power is supplied. The socket, in turn, is generally mounted to a support member. Many times the socket member is adjustable with regard to the support member to allow different aiming orientations of the light fixture.
One type of support member for multiple large lighting fixtures is a rigid elongated bar, beam or cross-arm which can be horizontally secured to a vertical light pole or the like or otherwise suspended. A common term for the bar, beam or cross-arm which supports multiple lights fixtures is a light bar. It is generally a rectangular-in-cross-section hollow tube, with closed ends. Conventional light bars are generally on the order of ten feet long allowing usually from one to four light fixtures to be secured along the light bar at spaced-apart positions.
In typical use, the light bar is suspended and the light fixtures are all angularly oriented or tilted downwardly and outwardly on the same side of the bar towards a target area. In other words, much of each light fixture is positioned on the same side of a vertical plane extending through the longitudinal axis of the bar. This causes the center of gravity of the light bar with attached light fixtures to move off of the light bar, and as a result, produces torsional force tending to urge the horizontal bar to be rotated around its longitudinal axis. If the light bar is freely suspended, such as with vertical cables, such rotation would occur, causing the light bar to roll forward in the direction of the outer ends of the outwardly extending lamps, and thus move the lamps away from their intended aiming. The light bar would then not be "level", as that term will generally be use herein.
This is normally not a problem with light bars which are rigidly attached to a suspending pole, beam, derrick or other suspension means. In these cases, because the cross-arm or light bar is rigid, and is in turn rigidly attached to a light pole or the like, any offset of center of gravity or imbalance cannot cause the bar to rotate or move in any direction. Rigid attachment prevents the torsional force from causing rotation of the light bar around its longitudinal axis.
However, there are many applications where large wide-scale light fixtures are desirable, but sturdy and rigid light poles are not desired or are not available. In many of these types of cases, the light bars and fixtures are or need to be suspended from some elevated structural support such as a ceiling beam or a boom. For example, the light bar could be suspended by cables, wires, or the like from the elevated structural support.
Although this presents an economical and relatively easy method for suspending large lighting fixtures, the imbalance of the lighting fixtures with respect to the light bar support member makes it difficult, or impossible, to keep the light bar level, or in a consistent, fixed aiming position. Although the cables can be fairly accurately and easily adjusted and maintained to keep the bar level in the sense that opposite ends of the bar are at an equal height from the floor, it is difficult to keep the bar level in the sense that it will not rotate or roll forward around its longitudinal axis towards the center of gravity, which is the leveling problem addressed here.
Essentially the problem to be solved is that the center of gravity of the light fixture is generally extended away from the support member when the light fixtures are aimed outwardly in the same general direction. The support member is somewhat unstable because it is being suspended by cables or the like. Thus, the offset center of gravity of the one or more light fixtures would cause the support member to rotate around its longitudinal axis. Additionally, this problem would not allow the light fixtures to be easily or accurately pre-aimed before the light bar is suspended, because the exact amount of rotation of the bar would not easily or reliably be known until suspended to its final position. Still further, if any one of the light fixtures needed to be re-aligned, it could very well affect the aiming of the other fixtures because of a rotation of the light bar on a change of a center of gravity.
It would be preferred, of course, if the cable-suspended support member could be adjustably and automatically held in what will be referred to as a "reference" or "level position" so that any offset center of gravity urging or causing the support member to rotate around its longitudinal axis could be corrected or compensated. In other words, it is desired that the support member be consistently held in a position similar to it being rigidly secured to a vertical support pole or the like. While leveling of the support member could be attempted by adding weights or other load leveling apparatus to the support member to counterbalance the light fixtures, the problem is not completely alleviated, especially if the position of the light fixtures with respect to the support member is adjusted or altered. This would also add considerable weight to the arrangement, be cumbersome, and inefficient.
Additionally, in some situations, the lighting fixtures are articulately mounted to the light bar. Their angular and directional orientation can thus be changed by manipulating a joint means for each fixture. See, for example, U.S. Pat. No. 4,450,507 to Gordin, issued May 22, 1984, entitled Composite Photometric Method. Thus, although a light bar might be balanced by counterweights or the like with the light fixtures in one position, any adjustment of any light fixture would generally result in some change in the center of gravity or balance which would unlevel the light bar. If this occurred, there would be no set frame of reference by which the aiming of the light fixtures could be accomplished. Also, adjustment of less than all of the fixtures would bring the remaining fixtures out of their intended aiming orientation.
Still further, there are means and methods by which the light fixtures can be remotely adjusted according to desire. For example, in U.S. Pat. No. 4,712,167, to Gordin and Drost, entitled "Remote Control, Moveable Lighting System," issued Dec. 8, 1987, there is disclosed a wide-scale lighting fixture having actuators associated with the fixture which respond to remote control from a radio transmitter or the like. The fixture can be panned or tilted, according to desire. This patent is incorporated by reference herein. Obviously, if the light bar with these adjustable multiple light fixtures were suspended from cables, the light bar may be generally level, that is, its top surface horizontal, if all fixtures were pointed directly downward from the bottom of the light bar. However, if any fixture were angularly oriented away from pointing directly downward, the center of gravity of the light bar would be altered and the light bar would rotate around its longitudinal axis. Remotely controlled light fixtures allow easy and flexible adjustment of the fixtures in a number of directions. Each adjustment would alter the bar's center of gravity and would therefore unlevel the light bar.
It would therefore be desirable to have a leveling means which could be used to maintain the light bar in a certain orientation (called "level position"), regardless of the orientation or aiming directions of the light fixtures (or any other structure) on the light bar, or any change in orientation or aiming direction of any light fixture on the light bar. The bar would be adjusted to always stay in reference or level position, even if the fixtures are adjusted in a manner to urge the bar to rotate around its longitudinal axis.
Furthermore, it is inefficient and cumbersome to manually level the light bar each time it is suspended or any fixture's orientation is changed. Because large, wide scale lighting fixtures most times must be suspended from very high positions, in many cases it is difficult or even impractical for leveling to be manually accomplished. It would therefore be desirable to have a leveling means which leveled the light bar when suspended. It would also be desirable to have a leveling means which could, if desired, automatically level the light bar when suspended.
It is therefore a principal object of the present invention to provide a leveling means for suspended light bars with lighting fixtures which solves or overcomes the problems and deficiencies in the art.
Another object of the present invention is to provide a means as above described which allows for leveling and maintaining the reference position of the light bar holding the light fixtures, with respect to rotational around its longitudinal axis, regardless of the orientation of the light fixtures, or the imbalance of the light fixtures or any other attachments or structure with regard to the light bar.
A further object of the present invention is to provide a means as above described which can level the light bar for the light fixtures, regardless of how many light fixtures are utilized.
A further object of the present invention is to provide a means as above described, which can automatically level the light bar supporting the light fixtures.
A further object of the present invention is to provide a means as above described which is non-complex, reliable, durable, and economical.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.